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## org.bouncycastle.crypto.macs
Class DSTU7624Mac

    java.lang.Object
      org.bouncycastle.crypto.macs.DSTU7624Mac

All Implemented Interfaces:
  Mac

public class DSTU7624Mac
extends java.lang.Object
implements Mac

Implementation of DSTU7624 MAC mode.

This is a CBC-MAC variant (a CBC chain whose final block is masked with kDelta = E(0) before the last encryption) and, like raw CBC-MAC, it is defined only for input that is a whole number of blocks: `doFinal(byte[], int)` rejects a trailing partial block with "input must be a multiple of blocksize". The restriction is deliberate and is not relaxed by zero-padding the final block. The MAC binds no message length, so zero-padding a partial block would make the tag of an N-byte message collide with that of a longer message sharing the same final block once padded (the documented ambiguity of ISO/IEC 9797-1 padding method 1). DSTU 7624:2014 specifies no partial-block padding for this MAC and publishes no vector for one, so any padding scheme BC chose (zero-pad, or the unambiguous 10* / ISO 9797-1 method 2 that CMAC uses) would be non-conformant and non-interoperable. Callers needing to authenticate arbitrary-length input should pad to a block boundary with an agreed scheme before calling update, or use a length-binding MAC such as KGMac. See github #287.

Constructor Summary
`DSTU7624Mac(int blockBitLength, int q)`

Method Summary
`int` | `doFinal(byte[] out, int outOff)` Compute the final stage of the MAC writing the output to the out parameter.
`java.lang.String` | `getAlgorithmName()` Return the name of the algorithm the MAC implements.
`int` | `getMacSize()` Return the block size for this MAC (in bytes).
`void` | `init(CipherParameters params)` Initialise the MAC.
`void` | `reset()` Reset the MAC.
`void` | `update(byte in)` add a single byte to the mac for processing.
`void` | `update(byte[] in, int inOff, int len)`

Methods inherited from class java.lang.Object
`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Constructor Detail

### DSTU7624Mac

    public DSTU7624Mac(int blockBitLength,
                       int q)

Method Detail

### init

    public void init(CipherParameters params)
              throws java.lang.IllegalArgumentException

  Description copied from interface: `Mac`
  Initialise the MAC.

  Specified by:
    `init` in interface `Mac`
  Parameters:
    `params` - the key and other data required by the MAC.
  Throws:
    `java.lang.IllegalArgumentException` - if the params argument is inappropriate.

### getAlgorithmName

    public java.lang.String getAlgorithmName()

  Description copied from interface: `Mac`
  Return the name of the algorithm the MAC implements.

  Specified by:
    `getAlgorithmName` in interface `Mac`
  Returns:
    the name of the algorithm the MAC implements.

### getMacSize

    public int getMacSize()

  Description copied from interface: `Mac`
  Return the block size for this MAC (in bytes).

  Specified by:
    `getMacSize` in interface `Mac`
  Returns:
    the block size for this MAC in bytes.

### update

    public void update(byte in)

  Description copied from interface: `Mac`
  add a single byte to the mac for processing.

  Specified by:
    `update` in interface `Mac`
  Parameters:
    `in` - the byte to be processed.

### update

    public void update(byte[] in,
                       int inOff,
                       int len)

  Specified by:
    `update` in interface `Mac`
  Parameters:
    `in` - the array containing the input.
    `inOff` - the index in the array the data begins at.
    `len` - the length of the input starting at inOff.

### doFinal

    public int doFinal(byte[] out,
                       int outOff)
                throws DataLengthException,
                       java.lang.IllegalStateException

  Description copied from interface: `Mac`
  Compute the final stage of the MAC writing the output to the out parameter.

  doFinal leaves the MAC in the same state it was after the last init.

  Specified by:
    `doFinal` in interface `Mac`
  Parameters:
    `out` - the array the MAC is to be output to.
    `outOff` - the offset into the out buffer the output is to start at.
  Throws:
    `java.lang.IllegalStateException` - if the MAC is not initialised.
    `DataLengthException` - if there isn't enough space in out.

### reset

    public void reset()

  Description copied from interface: `Mac`
  Reset the MAC. At the end of resetting the MAC should be in the in the same state it was after the last init (if there was one).

  Specified by:
    `reset` in interface `Mac`

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